LeetCode 28 - Implement strStr() Problem

Problem Statement

Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Example 1:

Input: haystack = "hello", needle = "ll"
Output: 2

Example 2:

Input: haystack = "aaaaa", needle = "bba"
Output: -1


What should we return when needle is an empty string? This is a great question to ask during an interview.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().


class Solution: def strStr(self, haystack: str, needle: str) -> int: if not needle: return 0 m=len(haystack) n=len(needle) if m<n: return -1 for i in range(m-n+1): counter=0 for j in range(n): if haystack[i+j]!=needle[j]: break counter+=1 if counter==n: return i return -1